Jupiter’s moon Io is the most geologically active place in the Solar System. This intense volcanism is due to the gravitational pull of the giant planet and its other three Galilean satellites, and the dense moon sports over 150 confirmed volcanoes. Now planetary scientists think they have found a new one.
The discovery of the hotspot was possible thanks to observations made by NASA’s Juno spacecraft. As it flew past the moon, one of its instruments picked up a heat signature that suggested a previously unidentified hotspot existed near Io's south pole. The orbiter is mainly studying Jupiter, its atmosphere, and its magnetic interaction so this is not a primary focus.
The Jovian InfraRed Auroral Mapper (JIRAM) instrument spotted the new heat spot on December 16, 2017, when the probe, busy on its 10th close approach of Jupiter, was just 470,000 kilometers (290,000 miles) from the moon.
"The new Io hotspot JIRAM picked up is about 200 miles (300 kilometers) from the nearest previously mapped hotspot," Alessandro Mura, a Juno co-investigator from the National Institute for Astrophysics in Rome, said in a statement. "We are not ruling out movement or modification of a previously discovered hot spot, but it is difficult to imagine one could travel such a distance and still be considered the same feature."
The Jovian system has been visited by several spacecraft and was studied in detail by the Galileo probe in the 1990s. Researchers have estimated that 400 volcanoes might be found on Io. This hot signature might be the first of many new discoveries related to the moon.
The team will continue to analyze the data from this flyby as it waits for closer inspections of Io. The four flybys that have happened since, with the latest one on July 16, didn’t allow for close inspection of the satellite. But future flybys will.
The Juno mission has been renewed and will continue to fly around Jupiter for at least another three years. The last currently scheduled flyby, number 35, will take place on July 30, 2021.